The first thing confronting visitors at Grimaldi’s Pizzeria on Old Fulton Street in Dumbo, Brooklyn, is a sign on the door that announces: “No Slices.” Only whole pies are available, and the fewer questions, the better.

But of course, the pizzeria’s founder, 75-year-old Patsy Grimaldi, has nothing to do with the restaurant these days, having sold it six years ago.

“I’ve been retired — it was a big mistake,” Mr. Grimaldi said. With the top-rated pizzeria in the Zagat guide no longer his, he found himself bored.

Now, however, after making pies at home in Rego Park, Queens, for his wife, Carol, and doting on their 10 cats, Mr. Grimaldi is back in action. At a yet-unnamed stand in a former airplane hangar at Floyd Bennett Field in southeastern Brooklyn, Mr. Grimaldi is again making pizzas the way he was taught by his Uncle Patsy in East Harlem at age 10. His new venture is part of the Brooklyn Food Hall of Fame, a food court of sorts inside Aviator Sports and Recreation, a two-month-old sports complex that will also offer local delicacies like Junior’s cheesecake and Jacques Torres chocolate.

As reported on Nov. 28 by sliceny.com, a pizza blog, Mr. Grimaldi’s emergence from retirement is startling to pizza buffs, and even more shocking is his agreement to sell individual slices. (They are $2.50.) But reaction to his return is far from negative.

“If it’s true that it’s Patsy Grimaldi doing it, then it’s going to be good,” said David Freedenberg, a local food blogger and a taxi driver who uses his cab to conduct food tours around the city. Mr. Freedenberg had another thought: “This slice might actually be perfect for the tour.”

Mike Pezzano, another devoted fan, volunteered another opinion. “It’s crispy, it’s nice, it’s fresh,” he said. And since Mr. Pezzano works as a security supervisor at Aviator — he could be found one day last week munching on a Grimaldi slice at the front door of the athletic complex — the location couldn’t be more convenient.

Meanwhile, Mr. Grimaldi is driving to Aviator every day, getting accustomed to working again. But training a young staff in his way of baking has been difficult. His urgent message to the public, he told a reporter, is “Pizza man wanted.”

“I did take one day off, and somebody else made the dough, which they shouldn’t have done,” said Mr. Grimaldi, a tall man in tinted glasses, as he pointed to hunks of dough that had expanded so much they were sticking together. He calmly flattened one mound with his fingertips, then spread around crushed plum tomatoes, two types of cheese and a few herbs before sliding it into the oven. Five minutes later, it came out perfect.